(a) Field of the Invention
The present invention relates to the combination device of the IC connection device and the main board. Especially, the present invention relates to a main board which is suitable to combine one of the pin-style socket and the ball-style socket.
(b) Description of the Prior Arts
For long time in prior art, there are two basic methods to place IC package on main board. One is to solder firmly the IC package on the main board but the IC package is not replaceable. The other method is that the IC package is replaceable, so the IC package can be replaced when necessary. Most of time, the replaceable combination device of the IC connection device and the main board is used when the IC device needs to be upgraded, the IC device itself needs to be replaced or in some cases that need expensive IC device. The replaceable IC device is used when one of the devices on main board is broken or needs to be replaced but the rest of the components on the board still in good condition, the combination device of the main board and the socket of the CPU is a best example.
Please refer to FIG. 1 and FIG. 2, which showing a conventional replaceable combination device 10 of the main board and the socket of IC device in prior art. In prior art, an IC device 11 has pins 111, and the main board 12 has a socket 13 with many pin holes 131 in order to connect each other in better electrical condition. There are two basic methods to seal down the IC device 11, one is called lead frame and the other is BGA. In recent years, another method called flip chip BGA packaging has been used more often in sealing high-numbered pins IC package. FIG. 1 shows the basic components which comprising an IC chip 112 placed on one side of the substrate 113 by flip chip method. Several solder balls 114 are placed on the other side of the substrate 113, which connecting the IC chip 112 and the substrate 113. The other side of the IC chip 112 has a heat sink 115. For the pins 111 is not hard enough, and it is easy to be broken during replacing. And for the pins 111 is not easy to connect the solder 114 firmly. So, before being soldered to the solder ball 114, it has to be placed on an interposer 116 with modeling technology.
In order to provide the function, the pins 111 of the IC device 11 will be placed. The socket 13 in prior art comprises a socket base 132 with a plurality of holes 131 soldered on the main board 12, a sliding board 133 which can slide linearly and a long levering bar 134 placed aside the socket base 132 to be used to move the sliding board 133 in a micro manner. The electrically conducting pad 137 is placed in every pin hole 131 of the socket 132. And the solder pad 135 is on the bottom part of the pin holes 131. The pin holes 131 are extended from the bottom part of the electrically conducting pad 137 in order to form the PTH (Plated Through Hole) 121 in the main board 12 for pins 1371. The electrically conducting layer 122 is set in the PTH 121 of the main board 12 in order to connect with pins 1371 electrically. The position of the contact pad 1221 and the PTH 121 on the upper surface of the main board 12 can be SMD (solder mask defined) or NSMD (none solder mask defined. The pins 1371 and the electrical connection device 13 are soldered on the main board 12 firmly by the materials 123 and 125 of the soldering. The larger holes on the sliding pad 133 corresponding to the pin holes 13 are set. Rotating the long stick 134 along the axle 136 to be parallel with the socket 132 will make the slider 133 move in micro manner and the pins 111 in IC package 11 be hold tightly in the pin holes 131. In order to take out the IC package 11, the long stick 134 can be rotated to be horizontal with the socket 132, and then the pins 111 can be released from the IC package 11.
Please refer to FIG. 3 which is the combination device 10a of the main board and the electrical connection device of the replaceable IC package in prior art. Because the IC package 11 and the electrical connection device 13a in prior art are similar to the devices in prior art in FIG. 1, additional description of the detailed element and the structure is not necessary, but shown in dashed lines. The main difference in FIG. 3 is that the combination device 10a is using several solder balls 138 but not the pin-style structures. Instead of PTH, the solder pad 126 is placed on the main board 12a by solder reflow of the solder ball 138 of the electrical connection device 13a and the solder pad 126 of the main board 12a. We can solder on the solder pad 126 firmly for the solder balls 138. The disadvantages in prior art are the intensity of the structure of the combination of the solder balls 138 and the solder pad 126 is weaker because the solder balls 138 and the solder pad 126 combine in plane-contact style. The disadvantage will lead to the increase of the defect of the products. Or the department of the solder balls 138 from the solder pad 126 will be possible. And the stability of the electricity and the short-circuit characteristics will happen because the overflow of the solder balls 138 in the solder reflow. In the same time, the co-planarity of the combination of the electrical connection device 13a and the main board 12a will be bad.
The pin-style electrical connection device in FIG. 1 in prior art and the ball-style electrical connection device 13a in FIG. 3 in prior art will use the corresponding main board 12 and 12a. Because the main board 12a in FIG. 3 will not provide the PTH to apply the usage of the pin-style electrical connection device 13. The PTH 121 in the main board 12 can apply the usage of the pin-style electrical connection device 13. The main board 12 with PTH 121 will be in solder reflow with the ball-style electrical connection device 13a according to the ratio of the Sn/Pb being 63/37 and the Eutectic temperature of the solder balls being 183 degrees. The working temperature is changed according to the different time period. The highest working temperature is 220 degrees. We can not provide the stable connection of the electricity and the function of the soldering firmly. So we will not find the both functions of the ball-style electrical connection device 13a and the pin-style connection device 13 which are applied to the same main board.
The primary aspect of the present invention is to provide the same combination device of the main board and the IC package connection device. We can apply the combination device to combine with one of the ball-style electrical connection device and the pin-style electrical connection device.
In another aspect of the present invention is to provide the combination device of the main board and the IC package connection device. By the way of changing the ratio of the Sn/Pb in solder balls on the bottom surface of the socket of the ball-style electrical connection device, the Liquidus temperature (totally melting temperature) of the solder balls will be changed to a proper value (higher than the Eutectic temperature). Thesemi-melting state of the solder balls will not be empty in the PTH in the solder reflow of the main board with PTH and the ball-style electrical connection device. A part of the semi-meltingsolder ball will be putted in a part of the PTH in order to make the solder ball be a mushroom-shape structure after the process of solder reflow to provide the good intensity of the structure of the combination, the co-planarity and the yield of the product.
To achieve the purposes described above, one of the embodiment of the present invention comprises a socket and a main board. Said socket includes the inputted assembly on the top surface of the socket being used to connect with the IC package electrically and some solder balls. The solder balls are on the bottom surface and are corresponding to the inputted assembly of the socket. Several PTH are in the main board and the positions of the PTH are corresponding to the positions of the solder balls. The Liquidus temperature of the solder balls is higher than the Eutectic temperature of the solder balls, Sn/Pb at ratio 63/37, in prior art. The difference of the Liquidus temperature of the solder balls will make the solder balls be controllable semi-solid state and make a part of thexe2x80x94semi-solid state solder ball be able to input to a part of the PTH in solder reflow process. In order to let the solder balls be the mushroom-shape structure and the upper-mushroom-shape part on the main board and the lower-mushroom-shape part inputted in a part of the PTH.
The appended drawings will provide further illustration of the present invention, together with the description, serve to explain the principles of the invention.